This invention relates to a water jet propulsion unit for watercraft and more particularly to an improved discharge nozzle arrangement for such a jet propulsion unit.
In one form of jet propulsion unit commonly used with watercraft, the jet propulsion unit is comprised of an outer housing that defines a water inlet portion, an impeller portion in which an impeller is contained for pumping water through the water inlet portion and a discharge nozzle portion through which the water pumped by the impeller is discharged for providing a propulsion force for the associated watercraft. Frequently, the watercraft is also steered by a steering nozzle that is pivotally supported on the discharge nozzle of the outer housing about a vertically extending steering axis. By pivoting the steering nozzle about this axis, a turning force can be associated on the associated watercraft.
With jet propelled watercraft, like other watercraft, the trim of the watercraft is important in providing good handling. If the trim is too high, then the watercraft will ride roughly and may tend to porpoise. On the other hand, if the trim is too low, then the watercraft performance will be deteriorated as it will tend to operate nose down and plow into the water.
It is, therefore, a principal object of this invention to provide an improved arrangement for adjusting the trim of a jet propelled watercraft.
It is a still further object of this invention to provide an improved trim adjustment that can be made through the steering nozzle of a jet propelled watercraft.
It is a still further object of this invention to provide an improved trim control arrangement for the steering nozzle of a jet propelled watercraft.
In addition to the forward motion, frequently it is desirable to provide an arrangement whereby the watercraft can be operated in a reverse mode. This is generally done by providing a reverse thrust bucket which cooperates with the discharge nozzle of the watercraft for providing a reverse thrust to the watercraft when the reverse thrust bucket is shifted to the reverse mode. This is done by redirecting the flow of water from the discharge nozzle in a forward direction.
However, where the jet propulsion unit employs a pivotally supported steering nozzle, it has been previously the practice to mount the reverse thrust bucket on the steering nozzle. This somewhat complicates the mounting arrangement and furthermore makes it necessary that the actuating mechanism for the reverse thrust bucket can accommodate steering movement without having this change the position of the reverse thrust bucket.
It is, therefore, a still further object of this invention to provide an improved reverse thrust bucket and mounting arrangement for a water jet propulsion unit.
In addition to the aforenoted difficulties, if the reverse thrust bucket is mounted on the steering nozzle, then the possibility of mounting the steering nozzle so that it can be moved for trim adjustment becomes much more complicated and difficult.
It is, therefore, a still further object of this invention to provide an improved reverse thrust bucket arrangement for a jet propelled watercraft wherein the steering nozzle of the jet propulsion unit is also mounted for pivotal movement about a horizontal axis in a trim controlling manner.